Reznor R8HE Unit Installation Manual Manual de usuario descargar pdf (Pagina 12)

• All208-240voltunitsareshippedfromthefactorywired

for 240 volt transformer operation. For 208V operation,

remove the lead from the transformer terminal marked

240V and connect it to the terminal marked 208V.

• Connecttheline-voltageleadstotheterminalsonthe

contactor inside the control compartment.

Unbalanced3-PhaseSupplyVoltage

Voltage unbalance occurs when the voltages of all phases

of a 3-phase power supply are no longer equal. This

unbalance reduces motor efﬁciency and performance.

Some underlying causes of voltage unbalance may

include:Lack of symmetryintransmission lines, large

single-phase loads, and unbalanced or overloaded

transformers. A motor should never be operated when a

phase imbalance in supply is greater than 2%.

Perform the following steps to determine the percentage

ofvoltageimbalance:

1. Measure the line voltages

of your 3-phase power

supply where it enters

the building and at a

location that will only

be dedicated to the

unit installation. (at the

units circuit protection or

disconnect).

EXAMPLE:

AB = 451V

BC = 460V

AC = 453V

2. Determine the average voltage in the power supply.

In this example, the measured line voltages were 451,

460, and 453. The average would be 454 volts (451 +

460 + 453 = 1,364 / 3 = 454).

3.Determinethemaximumdeviation:

EXAMPLE

From the values given in step 1, the BC voltage (460V)

isthegreatestdifferenceinvaluefromtheaverage:

460 - 454 = 6

454 - 451 = 3

454 - 453 = 1

4. Determine percent of

voltage imbalance by

using the results from

steps 2 & 3 in the following

equation.

454

100 x

= 1.32%

EXAMPLE

maxvoltage deviation

fromaverage voltage

=100 x

averagevoltage

% Voltage Imbalance

The amount of phase imbalance (1.32%) is satisfactory

since the amount is lower than the maximum allowable

2%. Please contact your local electric utility company if

your voltage imbalance is more than 2%.

Highest Value

Thermostat/LowVoltageConnections

• Thisunitisdesignedtooperatefroma24VACClassII

control circuit. A single stage cooling / two stage heating

thermostat should be used with this unit. See Figure 10

(page 36) for typical thermostat connection.

• Thecontrolcircuitwiringmustcomplywiththecurrent

provisions of the NEC (ANSI/NFPA 70) and with

applicable local codes having jurisdiction. Thermostat

connections should be made in accordance with the

instructions supplied with the thermostat and the indoor

equipment.

• The low voltage wires must be properly connected.

Route 24V control wires through the sealing grommet

near the power entrance. Recommended wire gauge

and wire lengths for typical thermostat connections are

listed in Table 18 (page 35).

• Several thermostat options are available depending

on the accessories installed with the unit. Select a

thermostat that operates in conjunction with the installed

accessories.

• Thethermostatshouldbemountedabout5feetabove

the ﬂoor on an inside wall. DO NOT install the thermostat

on an outside wall or any other location where its

operation may be adversely affected by radiant heat from

ﬁreplaces, sunlight, or lighting ﬁxtures, and convective

heat from warm air registers or electrical appliances.

Refer to the thermostat manufacturer’s instruction sheet

for detailed mounting information.

2-Stage Heat / 1-Stage Cool Thermostat

(Recommended): For highest efﬁciency a 2 Stage Heating/

Single Cooling thermostat is recommended for this unit. A

Single Stage Cool thermostat is only required for cooling

operation control of this unit. A 2 Stage Heat thermostat

will allow the gas heat to operate at a more efﬁcient low

heat condition until there is a demand for higher heat

output to the conditioned space.

Single Stage Heat / Single Stage Cool

Thermostat

(Optional):ASingleStageCoolthermostatisonlyrequired

for cooling operation of this unit. A Single Stage Heat

thermostat can be used in conjunction with the automatic

heat staging jumper on the ignition control board. The heat

staging function will automatically move the unit into high

heat operation after 10 minutes when the jumper is moved

from OFF to the ON position. See Figure 12 (page 36).

Connect the Red, Yellow, Green, White, and Brown low

voltage thermostat wires to terminals R, Y1 (1st Stage

Cool), G, W1 (1st Stage Heat), & W2 2nd Stage Heat-

optional) on both the thermostat sub-base and unit low

voltage terminal board. The C terminal (Black wire), is the

24V common wire required on some thermostat models.

See Figure 10 (page 36).

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Reznor R8HE Unit Installation Manual Manual de usuario Pagina 12

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